Another case of the new, mutant strain of mpox has been detected in London, the UK Health Security Agency (UKHSA) has announced.

       The total number of UK cases confirmed of the virus, identified as clade 1b, now stands at four – all within the same household, according to UKHSA.

       The agency reported the first case of the virus, previously known as monkeypox, last Friday in a patient who had recently returned to the UK from Africa. Two household contacts were subsequently confirmed to have been infected, followed by this third case.

       The patient is receiving specialist care at Guy’s and St Thomas’ NHS Foundation Trust.

       All four have been isolated and no additional contact tracing is required, the UKHSA said.

       “Mpox is very infectious in households with close contact and so it is not unexpected to see further cases within the same household. The overall risk to the UK population remains low,” Professor Susan Hopkins, Chief Medical Adviser at UKHSA.

       Clade 1b is a different variant from the ones that have been circulating in the UK since 2022. It is thought to cause more severe disease and spread more easily between people.

       The strain first emerged in the Democratic Republic of Congo (DRC) late last year. It has since infected more than 25,000 people and has been responsible for the deaths of at least 1,000, mainly children under the age of 15.

       The virus’s rapid spread triggered the World Health Organization to declare a global health emergency earlier this year, the same protocol taken in February 2020, shortly before Covid-19 spiralled into a pandemic.

       Cases have been reported in several countries in Africa, including Uganda, Burundi, and Rwanda. They have also been picked up in Sweden, Germany, India, and Thailand – all in people who had returned from affected areas.

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